1. Field of the Invention
The present invention relates to an apparatus which detects earthquake and stops the operation so as to prevent an accident. More particularly, it relates to an apparatus for operating an elevator during an earthquake.
2. Description of the Prior Art
A conventional apparatus which detects an earthquake in order to prevent an accident such as a conventional apparatus for operating an elevator during earthquake will be described.
It has been proposed to operate an elevator system which detects an earthquake and drives a cage to a nearby floor and opens its door and then, stops the operation. In such an operation for earthquake, it is preferable to detect an initial slight earthquake shock so as to switch the operation to the operation for earthquake and to stop the cage and to allow passengers to escape from the cage of the elevator before the main earthquake shock.
The device for detecting the initial slight earthquake shock is actuated, however, by even a weak earthquake which does not cause any damage to the elevator or a vibration caused by a construction near the building. Thus, needless operations of the elevator system in earthquake are disadvantageously often caused to prevent the normal operation of the elevator system.